Phenolic hydroxyl-containing resin by reacting epoxy resin with excess difunctional phenol and epoxidation thereof

ABSTRACT

A modified phenolic hydroxyl-containing resin having a low free difunctional phenol content and represented by general formula (1); a solid epoxy resin having an epoxy equivalent of 450 to 2,500 g/eq and prepared by epoxidizing the above resin; and another solid epoxy resin having an epoxy equivalent of 1,500 to 60,000 g/eq and a number-average molecular weight of 3,000 to 15,000 and prepared by reacting the above epoxy resin with a difunctional phenol compound. Resin compositions containing these resins have many applications as powder coatings and can paints. In formula (1), X represents a residue of a difunctional phenol compounds; X&#39;s may be the same or different; and n is the number of repeating units and is an integer of 0 or above. ##STR1##

CROSS-REFERENCE TO RELATED APPLICATION

This application is the national phase of International PCT applicationPCT/JP97/02293, filed Jul. 2, 1997.

FIELD OF THE INVENTION

This invention relates to a modified resin composition containingphenolic hydroxyl group and a curable resin composition thereof. Theinvention further relates to the epoxy resin composition which isobtained by epoxidation of said modified resin composition containingphenolic hydroxyl group by epihalohydrin and a curable resin compositionof said epoxy resin.

BACK GROUND OF THE INVENTION

In general, an epoxy resin composition is broadly applied as a componentof paint or adhesive and for various uses such as electric fields orcivil engineering because of the excellent chemical and physicalproperties which an epoxy resin composition originally has. However, therequired level for the features of epoxy resin composition are becominghigher and higher along with the progress of each field of application.Especially, in the uses of powder coating, molding materials or paintsfor inside surface coating of a can, the development of a resin whosecontents of lower molecular weight components is low is expected. Forinstance, since an epoxy resin powder coating has a good durability forcorrosion and has a strong resistance to chemicals, it is practicallyused as the paint for an inner and an outer surface coating of a steeltube or as the paint for a steel frame coating.

Generally, as an epoxy resin composition, bisphenol A type solid epoxyresin is used and as a hardener, dicyandiamide, acid anhydride, aromaticamine, dihydrazide or phenol resin is used. As a phenol resin which isused as the hardener, a novolac type phenol resin, preferably themodified resin which has a phenolic hydroxyl group at both ends can beused. For instance, the composition obtained by a chemical reactionbetween a bisphenol type epoxy resin composition obtained by reactingbisphenol such as bisphenol A or bisphenol F with epichlorohydrin underthe presence of hydroxide of alkali metal and excess bisphenol. As themodified resin which contains phenolic hydroxyl group, "TH-4100"produced by TOHTO KASEI, "EPICURE 171 and 172" produced by YUKA SHELLEPOXY and "XD-8062" of DOW CHMICAL are currently in the market. Thepowder coating which uses above mentioned modified resin as a hardeneris disclosed, for instance, in Japanese Patent Laid-open publication54-7473, Japanese Patent Laid-open publication 58-79011, Japanese PatentLaid-open publication 58-113267 and Japanese Patent Laid-openpublication 61-12762, and these powder coating are remarkably improvedso as to be applied to outer surface of a pipe. However, in theseconventional modified resins which contains phenolic hydroxyl group,since from 5 to 20 wt % of bisphenol A used for the reacted remains, andvaporizes at a baking procedure, following two phenomena are pointed outas serious problems. That is, accompanied with the vaporization ofbisphenol A, many tiny pin holes are formed on the surface of coatedfilm and the physical properties of coated film is deteriorated, furtherthe inside of a furnace for baking is polluted. Further, there isanother problem that, by the vaporization of bisphenol A, theanticipated mixing ratio with epoxy resin is changed and deterioratesthe physical properties of a coated film.

In the fields of powder coating and molding materials, conventionalbisphenol type solid epoxy resins have a problem of blocking anddeteriorate the stability of quality for storing, when a low epoxyequivalent resin is used. To solve the above mentioned problems, anepoxy resin not containing a low molecular component which causes ablocking problem, whose viscosity at molten state is low and has goodfluidity has been expected.

As a method to remove low molecular weight component in solid type epoxyresin, for instance, the method to remove low molecular weight componentby a molecular distillation is well known. However, even by this method,it is difficult to remove the low molecular weight component whosedegree of polymerization (hereafter shortened to n) is bigger than 0,further the problem that the solid epoxy resin is thermally decomposedby high temperature at the procedure of distillation has been pointedout. Furthermore, since it is necessary to repeat a distillation forseveral times to remove n=0 component completely, this method is notuseful for the industrial utilization. In the document of Japanese laidopen publication of 61-231018, the method to remove the low molecularweight component by contact with a hydrocarbon solvent such as xylene isreported, however by this method it is difficult to remove n=0 componentselectively and components bigger than n=0 are also removed and also theremoving effect of n=0 component is not sufficient. In Japanese patentlaid open publication 1-230678, the refined bisphenol type epoxy resinfrom which low molecular weight component i.e. lower than 800 is reducedor removed by contacting high molecular weight epoxy resin having 2000to 6000 number-average molecule weight with lower alcohol in an affinitysolvent is disclosed. This method is suited to a high molecule epoxyresin containing smaller than 2% of n=0 or n=l lower moleculecomponents, and the removing effect is not complete. The removing ofthese lower molecule components is not complete, even after 5 timesrepetition of rinsing procedure by alcohol, and is not an useful methodas an industrial use.

From the view point of sanitation, an epoxy resin composition which doesnot contain low molecular weight composition is expected. In general,for the use of inside surface coating of a can for beverage, anepoxy/phenol type coating, an epoxy/amino resin coating and anepoxy/urea resin coating are used.

However, recently, kinds of beverage to be packed in a can have becomemore diverse. Green tea, oolong tea and black tea are becoming morepopular as a beverage to be packed in a can. Since these kinds ofbeverage are heat treated by high temperature (retort treatment) afterbeing packed into cans, components of coating are partially dissolved atthis procedure and the lasting of flavor of contents is spoiled. As acoating which has good durability to bending at the can production, apolyvinyl-chloride organo# sol coating is usually used. However thiscoating has a problem of sanitation caused by monomer and plasticizerresidue, and also has an environmental problem caused by chlorine gasgenerated when the wasted cans are burned. Therefore, a development ofepoxy resin coating which has good durability to bending and anexcellent feature for lasting of flavor is desired.

The objects of this invention is to provide a modified resin containingphenolic hydroxyl group [A] which does not contain a vaporizingcomponent at a baking procedure and a curable resin composition thereof;a solid epoxy resin [B] which does not contain a low molecular weightcomponent and has a good fluidity and a curable resin compositionthereof; and a low molecular weight component free epoxy resin [C] whichforms a coating having good durability to bending and an excellentfeature for lasting of flavor and a curable resin composition thereof.

DISCLOSURE OF THE INVENTION

The important points of this invention include,

a modified phenolic hydroxyl group containing resin having a low freedifunctional phenol content comprising a resin [A] of formula (1), saidresin having a phenolic hydroxyl group equivalent of from 300 to 1,200g/eq; and, wherein residues of unreacted difunctional phenol is lessthan 5% by weight of resin, and a curable composition (a) comprising themodified phenolic hydroxyl group containing resin and an epoxy resin asthe necessary components;

an epoxy resin which is solid at room temperature [B] and whichcomprises the product of epoxidizing the modified resin withepihalohydrin, said epoxy resin having an epoxy equivalent in the rangeof from 450 to 2,500 g/eq and a curable resin composition (b) comprisingthe solid epoxy resin and a hardener;

an epoxy resin [C] which is solid at room temperature comprising theproduct obtained by the reaction of said solid epoxy resin anddifunctional phenol, said product having an epoxy equivalent of from1,500 to 60,000 g/eq and a number-average molecule weight of from 3,000to 15,000; and

an epoxy resin (c) characterized by a potassium permanganate consumptionvalue smaller than 5 mg O/L, whereis said value is measured on extractedwater which is prepared by adding, by a ratio of 1 ml water to 5 cm2area of unreacted dry film having a thickness of about 10 μm; and heattreated at 125° C. at high pressure for 1 hour in a sealed bottle andcurable resin composition comprising said solid epoxy resin and ahardener. ##STR2## (in forrnula (1), X represents a residue ofdifunctional phenol and n is 0 or a positive integer and wherein the X'sat different positions may be the same or different)

The modified resin containing phenolic hydroxyl group [A] represented byabove mentioned formula (1) can be produceed by a taffy method whichreacts difunctional phenol with epihalohydrin or by a fusion methodwhich reacts epoxy resin with difunctional phenol. Said two methods canbe preferably used. In a case of the taffy method, the modified resin[A] can be obtained by reacting epichlorohydrin with excessivedifunctional phenol in the presence of sodium hydroxide catalyst, thenremoving unreacted difunctional phenol. Meanwhile, in a case of thefusion method, the modified resin composition [A] can be obtained byreacting epoxy resin with excessive difunctional phenol, then removingunreacted difunctional phenol residue. The phenolic hydroxyl groupequivalent of the modified resin obtained by the direct and fusionmethod is desirably in the region of from 300 to 1200 g/eq; further, theresidue of difunctional phenol is desirably smaller than 5 wt %. Fromthe industrial view point, since the modified resin whose hydroxyl groupequivalent is smaller than 300 g/eq and bigger than 1,200 g/eq isdifficult to produce, the desirable region of hydroxyl group equivalentis from 350 to 800 g/eq and is more desirably from 400 to 700 g/eq. Ifthe residue of difunctional phenol is bigger than 5 wt %, the physicalproperty of curable composition is affected, therefore the amount ofresidue is desirably smaller than 1 wt %, and more desirably smallerthan 0.5 wt % and furthermore desirably smaller than 0.1 wt %.

As the difunctional phenol to be used for the synthesis of the modifiedresin containing phenolic hydroxyl group of this invention, bisphenol A,bisphenol F, bisphenol S, tetrabromobisphenol A, bisphenol AD, bisphenolC, catechol, resorcin, hydroquinone and others can be mentioned.Further, as the difunctional epoxy resin, the epoxy resin epoxidatedusing at least one kind of these difunctional phenol, hydrogenatedbisphenol A, 1,6 hexanediol, diglycidlethers of alcohol such aspolypropyleneglycol, hexahydrophthalic acid, diglycadlesters such asdimer acid and others can be mentioned, and especially a bisphenol typeepoxy resin is desirably used. As the bisphenol type epoxy resin, alower molecular weight type which is obtained by a taffy method isdesirably used, and especially a liquid epoxy resin of bisphenol A typeor bisphenol F type which is on the market as the general liquid type isdesirable.

To obtain the modified resin containing phenolic hydroxyl group by thetaffy method, excessive difunctional phenol is reacted withepichlorohydrin. Mole number of difunctional phenol to be added is from1.2 to 10 mole, desirably from 1.5 to 5 mole to 1 mole ofepichlorohydrin. When the mole number of difunctional phenol is smallerthan 1.2 mole, the molecular weight of obtained resin becomes too high.When it is bigger than 10 mole, the residue of difunctional phenolbecome too much to be removed and the commercial production becomesimpossible. Further, mole number of sodium hydroxide to be added is from0.7 to 1.2 mole to 1 mole of epichlorohydrin and is treated as thesolution from 8 to 15% concentration by weight. The taffy reaction canbe carried out within the limit of temperature from 40 to 120° C. for 1to 8 hours. Furthermore, said reaction can be carried out in a solutionwhich does not react with epoxy group. As the substantial examples ofthis solution, aromatic hydrocarbons such as toluene, xylene or benzene,ketones such as methylisobutylketone, methylethylketone, cyclohexanoneor acetone, glycolethers such as diethyleneglycolmethylether,propyleneglycolmethylether or dipropyleneglycolmethylether, aliphaticethers such as diethylether, dibutylether or ethylpropylether oralicyclic ethers such as dioxane or tetrahydrofuran can be mentioned.

To obtain the modified resin containing phenolic hydroxyl group by thefusion method, excessive difunctional phenol is reacted with epoxyresin. As in the direct method, mole number of difunctional phenol to bereacted with 1 mole of epoxy resin is from 1.2 to 10 mole, desirablyfrom 1.5 to 5 mole. As the difunctional phenols which are used for thefusion method, one or more kinds of afore# mentioned phenol can be used.When the mole number of difunctional phenol is smaller than 1.2 mole,the molecular weight of obtained resin becomes too high and consequentlythe fluidity of molten stage is deteriorated. When it is bigger than 10mole, the residue of difunctional phenol become too much to be removedand the commercial production becomes impossible. At the reaction, epoxyresin and difunctional phenol can be put in simultaneously, or epoxyresin can be added slowly into difunctional phenol. Further, thereaction can be carried out under the presence of catalyst within thelimit of temperature from 30 to 220° C. for 30 minutes to 6 hours,desirably from 80 to 160° C. for 1 to 6 hours. As the catalyst, metalhydroxide such as sodium hydroxide or potassium hydroxide, tertiallyamines such as 2-methylimidazole or 2-ethyl 4-methyl-imidazole,quaternary ammonium salts such as tetramethyl-ammoniumbromide orbenzyltrimethylammoniumbromide, phosphines such as triphenylphosphine ortributylphosphine, phosphonium salts such asn-butyltriphenylphosphonium-bromide can be mentioned. The desirableamount of catalyst to be added is from 10 to 10,000 ppm to difunctionalphenol used at the reaction. As in the direct method, the reaction canbe carried out in a solution, and the point when the epoxy group isvanished is regarded as the end point of the reaction.

After the reaction, as a method to remove the residue of unreacteddifunctional phenol, a method by solvent extraction, a method byrecrystallization, a method by molecular distillation, a method byseparating film, a removing method by dissolving in alkali aqueoussolution and others can be mentioned. From the industrial view point, amolecular distillation or a dissolving method in alkali aqueous solutionare preferably used. The removing method by dissolving in alkali aqueoussolution is illustrated as follows. After the direct or indirectreaction, afore# mentioned solution is added by the amount so as thesolid portion to be diluted to 20˜50 wt % concentration, then an alkalimetal hydroxide is added, reacted with the residue of difunctionalphenol and alkali metal phenolate is formed. Molar number of alkalimetal hydroxide to be added corresponds to 0.7 to 1.5 mole to 1 mole ofphenolic hydroxide group of difunctional phenol which is unreacted withthe formed modified resin having phenolic hydroxide group at the end.The reaction is carried out at the temperature of 30˜100° C., for 10minutes to 5 hours. Then, only alkali metal phenolate of difunctionalphenol is separated and removed from the high molecular product which isdissolved in the solution. As an alkali metal hydroxide, an aqueoussolution of sodium hydroxide or potassium hydroxide whose concentrationis smaller than 15 wt % may be used. When the concentration of aqueoussolution is bigger than 15 wt %, difunctional phenol is deposited. Thedesirable limitation of concentration is from 2 to 13% by weight. Almostwhole residue of difunctional phenol can be removed by one separatingoperation. After the removal of difunctional phenol residue, the productis neutralized by phosphoric acid or sodium phosphate and rinsed byfresh water, and the solvent is distilled out. Thus, the solid modifiedresin containing phenolic hydroxide group [A] whose phenolic hydroxideequivalent is from 300 to 1200 g/eq and in which difunctional phenoldoes not substantially is obtained.

The distinctive feature of curable composition [a] of this invention isthe use of said modified resin containing phenolic hydroxide group [A]with the epoxy resin as a hardener. As the epoxy resin there can beused, the epoxy resin which contains at least two epoxy groups in amolecule and whose melting point is from 50 to 140° C., which is usuallyused as a powder coating. For example, bisphenols such as bisphenol-Aand bisphenol-F, novolac type polyglycidylether such asdi-glycidylether, phenolnovolac and cresolnovolac, polyglycidylester ofpolycarboxylic acid and alicyclic epoxy resin can be mentioned, and onekind or a mixture of these compounds can be used.

As the modified resin containing phenolic hydroxide group [A] which isused as a hardener of the curable composition [a] of this invention thecompound whose phenolic hydroxyl equivalent is 300 to 1,200 g/eq isdesirable and 400 to 700 g/eq is more desirable. The desirable region ofsoftening temperature is from 50 to 140° C. and more desirable region isfrom 80 to 120° C. The desirable region of the amount for use ofmodified resin containing phenolic hydroxide group is from 0.6 to 1.5phenolic hydroxyl equivalent, more desirably from 0.6 to 1.0 equivalentto 1 epoxy group equivalent of epoxy resin. Further, as a hardener, acidanhydride or polyamine which are usually applied to a powder coating canbe used together with the modified resin of this invention as needed.

To the curable composition [a] of this invention, a color pigment suchas titanium oxide or carbon black, an extender such as calcium carbonateor talc, a rust preventive pigment such as zinc powder or aluminumphosphate, a filler material for reinforcement such as glass flakes orglass fiber, cure actuator such as 2-methylimidazole ortriethylphosphine, a flow control agent and a dispersing agent which areusually used in a powder coating and an ultraviolet absorber can beadded.

The curable composition [a] of this invention can be obtained by meltingand mixing an epoxy resin, a modified resin containing phenolichydroxide group and other additives as needed at the temperature of80˜120° C., then cooling down and crushing the solidified mixture. Asthe melting and mixing apparatus, a heating roller, a heating kneader oran extruder can be used. And the powder coating compound of thisinvention can be coated on the surface of an article by means of anelectrostatic painting method, fluidizing-bed coating method or others.The powder coating compound of this invention can be applied to areinforcement, a steel pipe and a deformed bar. The baking and curingcondition of the coated film is 180˜240° C. temperature for 1˜30 minutesand the article to be coated can be previously heated before coating.

The modified phenolic hydroxyl group containing resin of this invention[A] can be epoxidated by well known method which epoxidates a resin byepihalohydrin in the presence of alkali metal hydroxide, and a solidepoxy resin [B] which has 450˜2500 g/eq epoxy equivalent value can beobtained. As the kind of epiiodohydrin to be used in this application,epichlorohydrin, epibromohydrin and epiiodidehydrin can be mentioned andespecially epichlorohydrin can be preferably used. As the alkali metalhydroxide, sodium hydroxide can be preferably used. Excessive amount ofepihalohydrin of 2˜30 mole, desirably 10˜20 mole is added to 1 mole ofphenolic hydroxide group of material resin, and the amount of alkalimetal hydroxide to be used is from 0.7 to 1.1 mole to phenolic hydroxidegroup equivalent of material. It is desirable to react at thetemperature from 40 to 120° C. region while removing the generatedwater.

After the reaction, the excess epihalohydrin is vaporized off, then thereacted product is dissolved into afore# mentioned solvent, andpurifying reaction is made by adding 1 to 50 mole of alkali metalhydroxide to the hydrolyzable chlorine of generated epoxy resin. Byremoving byproduct salt by washing with water or by filtration andremoving solvent by vaporization, the epoxy resin [B] which is solid atroom temperature whose epoxy equivalent is from 450 to 2,500 g/eq can beobtained. The epoxy resin whose epoxy equivalent is smaller than 450g/eq has a problem of productivity at the production of solid resin, andthe epoxy resin whose epoxy equivalent is bigger than 2,500 g/eq isdifficult to remove the solvent after epoxidation.

Since the epoxy resin [B] which is solid at room temperature of thisinvention does not contain low molecular weight component, and furthersince the proportion of high molecular weight component can be decrease,the distribution of molecular weight is sharper than that of well knownsolid epoxy resin. The viscosity of the epoxy resin in the molten stateis low and the glass transition temperature of it becomes higher,further it has a good resistance to blocking and has a good fluidity.

The curable composition [b] of this invention is composed at least bysaid solid epoxy resin [B] and a hardener. As the hardener, conventionalhardeners which are used for hardening of an epoxy resin can be used.For instance, amines such as diethylenetriamine, triethylenetriamine,isophoronediamine, methaxylenediamine or diaminodiphenyl-methane, acidanhydride such as phthalic anhydride, hexahydro phthalic anhydride,nadic anhydride and trimellitic anhydride, polyester resin having acidfinctional end group, aminopolyamide resin which is a condensationproduct of dimer acid between diethylenetriamine or triethylamine,polysulfido resin which has mercaptan group at the end, borontrifluoride amine complex, novolac resin obtained by condensationreaction between phenols and formalin, any kind of compound which hasphenolic hydroxyl group, dicyandiamide, adipic dihydrazide, organic aciddihydrazide such as sebacic dihydrazide, polyisocyanates, imidazoles,resol phenol resin and amino resin can be mentioned.

To the curable composition [b] of this invention, at least one kind ofconventional epoxy resin selected from the group mentioned below can beadded at need. That is, for instance, polyglycidylether of bisphenolssuch as bisphenol A and bisphenol F, polyglycidylether of alcohol suchas polyethyleneglycol or polypropyleneglycol, polyglycidylester ofhexahydrophtalic acid or dimer acid, polyglycidylamine such asdiaminodiphenylmethane and novolak type polyglycidylether such as phenolnovolak or cresol novolak can be mentioned. Further, a filler, a diluentor an accelerator can be added at need. The curable composition [b] ofthis invention can be used for various uses, for instance as a coatingsuch as an anti-corrosive paint, powder coating, PCM paint or cannedpaint, an use to a civil engineering and construction industry, materialas an adhesive, an use to an electric and electronics industry componentsuch as an electric insulation (powder type) or a virtual adhesive forsemiconductor chip or as a composite such as a laminate (printed circuitboard) or a carbon fiber reinforced plastic (CFRP).

By addition polymerization reaction between solid epoxy resin [B] anddifunctional phenol, an epoxy resin which is solid at room temperature[C] whose epoxy equivalent is from 450 to 2,500 g/eq and anumber-average molecular weight is from 3,000 to 15,000 can be obtained.This solid epoxy resin [C] is an epoxy resin of high molecular weightwhich does not contain water extractive low molecular weight component.Therefore, a distinctive feature of this resin is that the potassiumpermanganate consumption value measured on extracted water is smallerthan 5 mg O/L. This extracted water is prepared by following procedure;add distilled water to the coated resin film by the proportion of 1 mlof distilled water to 5 cm² area of unreacted dry film of said uncuredresin having 10 μm thickness, heated in sealed bottle at the temperatureof 125° C. for 1 hour, and the obtained extracted water is used for themeasurement. Therefore, said solid epoxy resin [C] is suited for the useof an inner surface coating of canned beverage, which requires goodhygiene and good maintenance of flavor.

As the difunctional phenol which can be used for additionpolymerization, bisphenol A, bisphenol F, bisphenol S,tetrabromobisphenol A, bisphenol AD, bisphenol C, catechol, resorcinolor hydroquinone can be used, and one kind or the mixture of more kindsof these can be used. Among those, bisphenols such as bisphenol A andbisphenol F is desirably used.

Generally, the addition polymerization can be completed in the presenceof catalyst by reacting at the temperature of 80˜220° C. for from 30minutes to 20 hours. As the catalyst, same kinds and same amount ofcatalysts which are used in the case of said modified phenolic hydroxylgroup containing resin [A] can be desirably used. That is, alkali metalhydroxides, tertiary amines, imidazoles, quaternary ammonium salts,phosphines or phosphonium salts can be mentioned. At the preparation ofsolid epoxy resin [C], the reaction can be carried out in the solventwhich does not react with epoxy group. As the substantial examples ofthis solution, aromatic hydrocarbons such as toluene, xylene or benzene,ketones such as methylisobutylketone, methylethylketone, cyclohexanoneor acetone, glycolethers such as diethyleneglycolmethylether,propyleneglycolmethylether or dipropyleneglycolmethylether, aliphaticethers such as diethylether, dibutylether or ethylpropylether oralicyclic ethers such as dioxane or tetrahydrofuran can be mentioned.

Epoxy equivalent of solid epoxy resin [C] of this invention is desirablyto be in the region from 1,500 to 60,000 g/eq. When the epoxy equivalentis smaller than 1,500 g/eq, processsbility after being coated is notsufficient and when it is bigger than 60,000 g/eq, the production inindustrial scale becomes very difficult. And when the number-averagemolecular weight is smaller than 3,000, processability after beingcoated is not sufficient and when it is bigger than 15,000, theproduction in industrial scale becomes very difficult.

As the hardener component of the curable composition [c] of thisinvention, generally a substance which is used as a hardener of epoxyresin can be used, especially, resol resin and amino resin aredesirable. As the resol resin, for instance, a condensation product ofphenols such as phenol, alkyl phenols or bisphenols with aldehydes suchas formaldehyde or acetoaldehyde under the presence of basic catalystand alkyletherficated compound of it with alcohols such as methanol,n-butanol or isobutanol can be mentioned. On the other hand, as theamino resin, a condensation product of urea, melamine or benzoguanaminewith formaldehyde in the presence of basic catalyst andalkyletherficated compound of it with alcohols can be mentioned.

At the production of the curable composition [c] of this invention, onekind alone or a mixture of more kinds of these hardener components canbe used in accordance with need. And the blending amount of the curablecomposition [c] is to be within the region from 1 to 50% by weight tothe total weight of compound. When the blending ratio of the curablecomposition [c] is smaller than 1 wt %, the cross linkage of resin isnot sufficient and a retort resistance of coated film is not good, andwhen it is bigger than 50 wt %, the processing and bending feature of itare not good. The curable composition [c] of this invention can be usedwithout solvent or by dissolving it in solvent at need. Any kind ofsolvent which can dissolve the composition homogeneously can be used.

The curing composition [c] of this invention can be used as the watersoluble paint, by dispersing said solid epoxy resin [C] in water by wellknown method, for example, a method to partially esterfy it with theacrylic resin which has carboxylic group in the presence of esterfyingcatalyst, or a method to copolymerize with unsaturated monomer which hascarboxylic group in the presence of free radical generating agent.

The curable composition [c] of this invention can be used together witha reaction accelerating agent at need, for example, a curing catalystsuch as phosphoric acid or paratoluenesulfonic acid. Further, to thecurable composition [c] of this invention, various additives which areusually used in epoxy resin coating such as a filler, a reinforcingagent, a pigment or fluid controlling agent can be added at need.

As the method to coat the curable composition [c] of this invention, thewell known method such as a spray method, a roll coating method, amethod by brush or a method by pouring can be mentioned. In general, thecurable composition [c] of this invention is baked at the temperaturefrom 120 to 300° C. for 30 seconds to 20 minutes and the coated film canbe obtained.

BRIEF ILLUSTRATION OF THE DRAWING

FIG. 1 is a GPC chart of the modified phenolic hydroxyl group containingresin obtained in Example 1 [A-1], FIG. 3 is a chart indicating InfraRed spectrum of this modified phenolic hydroxyl group containing resin[A-1], while FIG. 2 is a GPC chart of the modified phenolic hydroxylgroup containing resin used in the Comparative Example 1.

FIG. 4 is a GPC chart of the solid epoxy resin [B-1] obtained in Example5.

FIG. 6 is a chart indicating Infra Red spectrum of this solid epoxyresin [B-1].

FIG. 5 is a GPC chart of the solid epoxy resin of Comparative Example 4.

FIG. 7 is a GPC chart of the solid epoxy resin [C-3] obtained in Example13.

FIG. 9 is a chart indicating Infra Red spectrum of this solid epoxyresin [C-3].

FIG. 8 is a GPC chart of the solid epoxy resin of Comparative Example 7.

In FIGS. 1, 2, 7 and 8, the vertical axis indicates amount of response(mV) and horizontal axis indicates the eluting time (min). In FIGS. 4and 5, the vertical axis indicates amount of response (%) and horizontalaxis indicates eluting time (count number). Furthermore, in FIGS. 1, 4,5 and 7, the eluting time (horizontal axis) in calibration curve andlogarithms of the molecular weight (vertical axis; log M) are plottedconcurrently. Further, in FIGS. 3, 6 and 9, the vertical axis indicatestransmittance and the horizontal axis indicates wave length.

THE BEST EMBODIMENT TO CARRY OUT THE INVENTION

The present invention will be understood more readily with reference tothe following Examples, however, these Examples are intended toillustrate the invention in detail and are not to be construed to limitthe scope of the invention. And in all Examples and Comparative

Examples, parts of proportion of each components are indicated by partsby weight.

EXAMPLE 1

In a reacting vessel equipped with a stirrer, a thermometer and acooling tube, 300 parts of YD-128 (Product of TOHTO KASEI; epoxyequivalent is 186 g/eq, viscosity is 12500 MPa·s/25° C.) as an epoxyresin, 364.9 parts of bisphenol A as a difunctional phenol are added.After molten at 120° C., 0.2 parts of triphenylphosphine is added as acatalyst and reacted at 170° C. for 3 hours. 1666 parts ofmethylisobutylketone and 1156 parts of 6.6% aqueous solution of sodiumhydroxide are added, stirred at 90° C. for 30 minutes then settled down,and the aqueous layer is separated. Further, the solution containingresin is neutralized by phosphoric acid, rinsed by water,methylisobutylketone is vaporized off, then light yellow colouredmodified resin composition containing phenolic hydroxyl group [A-1] isobtained. The hydroxyl group equivalent of obtained resin is 664 g/eq,the softening point is 105° C. and the residue of difunctional phenol(bisphenol A) is less than 0.1%. In this Example, the hydroxyl groupequivalent is measured by following procedure. In the mixture solutionof tetrahydrofuran and methanol 3 wt %, tetramethylammoniumhydroxide isacted upon phenolic hydroxyl group and develops color. Transmittance at305 nm is measured by a spectrophotometer and the hydroxyl groupequivalent is calculated by converting the transmittance value using thecalibration curve, which is prepared by same procedure using thestandard difunctional phenol (bisphenol A) used as starting material.The softening point is measured by JIS K-7234 method, and the residue ofdifunctional phenol is measured by GPC analysis. FIG. 1 is a GPC chartof said modified resin composition containing phenolic hydroxyl group[A-1] and FIG. 3 is a chart indicating infra red spectrum transmittanceof it.

EXAMPLE 2

In the same reacting vessel of Example 1, 200 parts of YD-128 and 608parts of bisphenol A are added. After molten at 120° C., 0.2 parts oftriphenylphosphine is added and reacted at 150° C., for 5 hours. 1153parts of methylisobutylketone and 1908 parts of 10.7% aqueous solutionof sodium hydroxide are added, stirred at 90° C. for 30 minutes thensettled down, and the aqueous layer is separated. Further, the solutioncontaining resin is neutralized by phosphoric acid, rinsed by water,methylisobutylketone is vaporized off. The hydroxyl group equivalent ofobtained resin [A-2] is 435 g/eq, the softening point is 97° C. and theresidue of bisphenol A is less than 0.1%.

EXAMPLE 3

100 parts of bisphenol A type solid epoxy resin EPO TOHTO YD-014(product of TOHTO KASEI; epoxy equivalent is 950 g/eq, softening pointis 100° C.), 49 parts of modified resin containing phenolic hydroxylgroup [A-1] obtained in Example 1, 1.0 part of 2-methylimidazol, 40parts of titanium oxide and 0.8 parts of MODAFLOW as a fluid controllingagent are blended in dry condition, then melt kneaded by an extruder(IKEGAI TEKKO, PCM-30). After cooled down, mulled to fine particles anda powder coating composition [a-1] is obtained.

The obtained powder coating composition is coated by powderelectrostatic painting method over the surface of steel plate(150×70×1.2 mm) whose surface is processed by sand blast and ispreviously heated to 240° C., then the specimen having about 200 μm filmthickness is obtained.

An appearance, a resistance to impact, a cathode exfoliation and aresistance to corrosion are measured and the obtained results are shownin table 1. The measuring methods are illustrated as follows.

Appearance

◯: good

Δ: slightly inferior (few pin holes are observed)

X: inferior (many pin holes are observed)

Resistance to impact

The coated test piece board is cooled down to 0° C., and -20° C., andthe resistance to impact at these temperature is measured by Gardnertester.

Cathode peeling test

Measured by ASTM G-8 method. Use 3% aqueous solution of sodium chlorideand the electric current is charged at 6 volt. After 30 days theresulting coating is peeled compulsory by knife. The numerical values inTable 1 are the averaged value the width measured in compulsory peelingof 8 directions from the coated film deficit portion of 5 mm Φ whichlocates at the center of test piece.

Resistance to corrosion

Cross cut line is marked on the surface of coated test piece and testedby anti salt water spray method disclosed in JIS K 5400. After beingsprayed with salt water for 500 hours, the coated film is peeledcompulsory by knife. The numerical value in Table 1 are the measuredvalue of width of peeling from the cross cut line.

EXAMPLE 4

By the same procedure as in Example 3 except using 32 parts of phenolichydroxyl group containing modified resin [A-2] obtained in Example 2,the powder coating composition [a-2] and the coated test piece ofExample 4 are obtained.

COMPARATIVE EXAMPLE 1

By the same procedure as in Example 3 except using 27 parts ofEPICURE-127 (product of YUKA SHELL EPOXY; hydroxide equivalent is 365g/eq, softening point is 87° C., residue of bisphenol A is 16.7% therewas), obtained the coated test piece of Comparative Example 1. GPC chartof phenolic hydroxyl group containing modified resin used in thiscomparative Example is shown in FIG. 2.

COMPARATIVE EXAMPLE 2

By the same procedure as in Example 3 except using 53 parts of TH4100(product of TOHTO KASEI; hydroxide equivalent is 721 g/eq, softeningpoint is 110° C., residue of bisphenol A is 5.5% there was), obtainedthe coated test piece of Comparative Example 2.

                  TABLE 1                                                         ______________________________________                                                     Example       Compar. Ex.                                                     3    4        1       2                                          ______________________________________                                        Appearance     ◯                                                                        ◯                                                                          X     Δ                                    Impact Resistance                                                             0° C. 1.6 1.7 0.9 1.3                                                  -20° C. 1.5 1.5 0.7 1.0                                                Cathode peeling 6˜8 5˜7 10˜12 8˜10                    Corrosion resistance 2 2 8 5                                                ______________________________________                                    

EXAMPLE 5

In a reaction vessel which equipt with a stirrer, a thermometer,dropping apparatus and the reacted water recovery apparatus, 130 partsof phenolic hydroxyl group containing modified resin [A-2] obtained inExample 2 and 260 parts of epichlorohydrin is added. After the resin isdissolved under the vacuum condition, the inside temperature of vesselis raised to 80° C., 18.6 parts of 49% aqueous solution of sodiumhydroxide is dropped for 2 hours. During this 2 hours, the temperatureof reaction system is kept at 80 to 85° C., and water generated byreaction and water contained in aqueous solution of sodium hydroxide isremoved from the reacting system as an azeotropic mixture withepichlorohydrin, and vapor is condensed; epichlorohydrin is recycled tothe system.

After the dropping of aqueous solution of sodium hydroxide, the insidepressure of vessel is returned to the atmospheric pressure, aged for 2hours and excess epichlorohydrin is vaporized off. To the mixture ofgenerated epoxy resin and sodium hydroxide, 245 parts of MIBK(methylisobutylketone) and 150 parts of water are added so as todissolve the contents, settled down for 30 minutes, then water are layeris separated. Further, 14.1 parts of 20% aqueous solution of sodiumhydroxide is added and refining reaction is carried out for 2 hours at80 to 85° C. After the reaction, 40 parts of MIBK and 150 parts of waterare added and the temperature raised to 80° C. Then after settling downfor 30 minutes the water layer are separated. The contents isneutralized by adding 5 parts of aqueous solution of 10% sodiumphosphate and 100 parts of water and separated, further rinsed by 100parts of water, separated and dehydrated. After being filtered, MIBK isvaporized off and the solid epoxy resin [B-1] is obtained.

GPC chart of its obtained solid epoxy resin is shown in FIG. 4, and thechart of infra red spectrum chart is shown in FIG. 6. Further, the epoxyequivalent of the resin, softening point, amount of n=0, n=1 and n=2contents, number-average molecular weight (Mn), weight-average molecularweight (Mw), Mw/Mn and glass transition temperature are summarized inTable 2.

The measuring method of each item in Table 2 is conformed to followingmethods.

Epoxy equivalent; Measured by JIS K-7236

Number-average molecular weight (Mn), weight-average molecular weight(Mw), Mw/Mn;

By GPC analysis by following condition, Contents of n=0, n=1 and n=2components are calculated from area percentage.

Analytical condition of GPC

Apparatus; TOSOH, HLC-802A type

Solution; THF

Column; TOSOH, 1 section of TSK-GEL and G2000H, 1 piece of G3000H

And 1 piece of G4000H

Temperature of column; 40° C.

Moving bed; THF

Flow rate; 1.5 ml/min

Detector; TOSOH, R1-8 type

Calibration curve; DGEBA

Glass transition temperature (Tg); Analyzed by Differential

scanning calorimeter (DSC) by the condition of temperature raising rate10° C./min.

EXAMPLE 6

In the same reaction vessel as in Example 5, 150 parts of modifiedphenolic hydroxyl group containing resin [A-1] obtained in Example land330 parts of epichlorohydrin are introduced. After the resin isdissolved, the temperature of system is raised to 80° C. 16.2 parts of49% aqueous solution of sodium hydroxide is dropped for 2 hours.

Similarly to Example 5, after maturing reaction, refining reaction,neutralization, rinsing, dehydration and filtration MIBK is vaporizedoff. Thus the solid epoxy resin [B-2] is obtained. The physicalproperties are shown in Table 2.

EXAMPLE 7

In a reaction vessel which equipt with a stirrer, a thermometer andcooling tube, 221.8 parts of bisphenol A and 224.9 parts of 10% aqueoussolution of sodium hydroxide are added and the temperature is raised to60° C. After the resin is dissolved, 50 parts of epichlorohydrin isdropped for 30 minutes and then reacted at 90° C. for 1.5 hours. 411parts of methylisobutylketone (MIBK) is added and contents is dissolved,further 853 parts of 5% aqueous solution of sodium hydroxide is addedand dissolved, and water layer is separated. Resin layer is neutralizedby phosphoric acid, rinsed by fresh water and dehydrated. Afterfiltration, solution is evaporated off and the phenolic hydroxyl groupcontaining modified resin [A-3] whose phenolic hydroxide equivalent is402 g/eq and softening point is 95° C. is obtained.

In a reaction vessel which equipt with a stirrer, a thermometer,dropping apparatus and the reacted water recovery apparatus, 130 partsof phenolic hydroxyl group containing modified resin [A-3] obtained asabove and 220 parts of epichlorohydrin and 44 parts ofdiethyleneglycol-dimethylether are added. After the resin is dissolvedunder vacuum condition, the inside temperature of the vessel is raisedto 80° C., 18.53 parts of 49% aqueous solution of sodium hydroxide isdropped for 1 hour. During this 1 hour, the temperature of reactingsystem is kept at 80 to 85° C., and water generated by reaction andwater contained in aqueous solution of sodium hydroxide is removed fromthe reaction system as a mixture of azeotropy with epichlorohydrin, andvapor is condensed, then epichlorohydrin is returned to the system.After the dropping of aqueous solution of sodium hydroxide, the insidepressure of vessel is returned to the atmospheric pressure, aged for 2hours and excess epichlorohydrin is vaporized off. To the mixture ofgenerated epoxy resin and sodium hydroxide, 275 parts of MIBK and 200parts of water are added so as to dissolve the contents, settled downfor 30 minutes, then water layer is separated. Further, 5.9 parts of 20%aqueous solution of sodium hydroxide is added and refining reaction iscarried out for 2 hours at 80 to 85° C. After the reaction, 200 parts ofwater added and the temperature raised to 80° C. Then settled down for30 minutes and water layer is separated. The contents is neutralized byadding 5 parts of aqueous solution of 10% sodium phosphate and 200 partsof water and separated, further rinsed by 100 parts of water, separatedand dehydrated. After filtrated, MIBK is vaporized off and the solidepoxy resin [B-3] is obtained. The obtained physical properties of epoxyresin are shown in Table 2.

COMPARATIVE EXAMPLE 3

The physical properties of conventional solid type epoxy resin YD-012(product of TOHTO KASEI) which is on the market produced by taffy methodof bisphenol A and epichlorohydrin are shown in Table 2.

COMPARATIVE EXAMPLE 4

The physical properties of conventional solid type epoxy resin YD-013(product of THOTO KASEI) which is on the market produced by taffy methodof bisphenol A and epichlorohydrin are shown in Table 2. FIG. 5 is theGPC chart of this resin.

The physical features of epoxy resin of Examples 5, 6 and 7, andconventional epoxy resin on the market disclosed in Comparative Example3 and 4 are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                   Example       Compar. Ex.                                          analytical items                                                                           5       6       7     3     4                                    ______________________________________                                        Epoxy equivalent g/eq                                                                      608     847     653   648   853                                    Softening point ° C. 84 95 79 80 91                                    GPC                                                                           n = 0 contents % 0 0 0 5.8 3.5                                                n = 1 contents % 0 0 11.4 8.8 6.3                                             n = 2 contents % 38.9 20.6 16.9 10.8 7.9                                      Mn 1310 1740 1288 1223 1640                                                   Mw 1810 2730 1730 2156 3320                                                   Mw/Mn 1.38 1.57 1.34 1.76 2.02                                                Glass transition 46 58 48 41 47                                               temperature                                                                 ______________________________________                                    

EXAMPLE 8

100 parts of epoxy resin [B-1] obtained in Example 5, 3.8 parts ofdicyandiamide, 0.2 part of 2-methylimidazole, 40 parts titanium oxideand 0.5 parts of MODAFLOW as a flow controlling agent are blended in drycondition and melt mulled by an extruder (IKEGAI TEKKO; PCM-30). Aftercooled down, milled to fine particles and the powder coating [b-1] isobtained.

The melting and milling conditions of extruder are;

Cylinder 1cooling

Cylinder 2; 80° C.

Cylinder 3; 90° C.

Head; 110° C.

Main screw; 200 rpm

Feeding screw; 20 rpm

The obtained powder coating is coated by powder electrostatic paintingmethod over the surface of steel plate (150×70×0.8 mm) whose surface isprocessed by sand blasting process and baked in 200° C. heated oven,then a coated test piece which has about 100 μm film thickness isobtained. A blocking resistance and a flowability of powder coating, aluster of coated film, a adhesive strength, Erichsen value and an impactresistance of the test piece are evaluated, and the results are shown inTable 3.

The evaluating method of powder coating and cured coated film are asfollows.

Resistance to blocking; Powder coating is placed in thermostat of 40° C.for 10 days, then the state of blocking is inspected. (◯; flowable, X;not flowable)

Flowability; 0.5 g of powder coating is picked up and a tablet of 13 mmdiameter is prepared by 100 kg/cm2 pressure at room temperature. Thistablet is placed on a steel plate having an inclination of 30 degreesand is left in 200° C. controlled oven. The distance that the coatingflows down, and the flowability is calculated by following numericalequation.

flowability=[distance of flow (mm)-13 (mm)]/thickness of tablet(mm)

Gloss; Gloss(%) is measured by JIS K 5400, 6.7 (60 degrees mirrorreflecting)

Adhesive strength; After a coated test piece is dipped into water andheat treated at 100° C. for 2 hours, 100 squares checker mark of Imm Xlmm square are cut on the coated surface by a knife and cellophane tapeis stuck, then the stuck tape is removed rapidly. Number of squares aremeasured by naked eyes.

Erichsen value, Using Erichsen tester, ponch is pushed out 10 mm andpinholes on coated surface is observed. (◯; no pinhole, X; pinholes canbe observed)

Resistance to impact Measured by JIS K-5400 method. By DU'PONT impacttester, 1/2 inch hammer and corresponding table are used and a weight of1 kg is dropped down from 50 cm height, and cracks and peeling areobserved by naked eyes of inspectors. (◯; normal, X; cracks and peelingscan be observed on the coating surface)

EXAMPLE 9

By the same blending, mulling, cooling and milling procedure to Example8 except using the epoxy resin [B-2] obtained in Example 6 the powdercoating [b-2] is obtained. The obtained powder coating is coated bypowder electrostatic painting method and baked, and the coated testpiece of Example 9 is obtained. This test piece is evaluated likely toExample 8, and the results are shown in Table 3.

EXAMPLE 10

By the same blending, mulling, cooling and milling procedure to Example8 except using the epoxy resin [B-3] obtained in Example 7 the powdercoating [b-3] is obtained. The obtained powder coating is coated bypowder electrostatic painting method and baked, and the coated testpiece of Example 10 is obtained. This test piece is evaluated likely toExample 8, and the results are shown in Table 3.

COMPARATIVE EXAMPLE 5

By the same blending, mulling, cooling and milling procedure to Example8 except using the epoxy resin obtained in Comparable Example 3 thepowder coating is obtained. The obtained powder coating is coated bypowder electrostatic painting method and baked, and the coated testpiece of Comparative Example 5 is obtained.

COMPARATIVE EXAMPLE 6

By the same blending, mulling, cooling and milling procedure to Example8 except using the epoxy resin obtained in Comparable Example 4 thepowder coating is obtained. The obtained powder coating is coated bypowder electrostatic painting method and baked, and the coated testpiece of Comparative Example 6 is obtained.

The evaluation results of coating film of powder coating of Examples 8,9 and 10, and Comparative Example 5 and 6 are shown in Table

                  TABLE 3                                                         ______________________________________                                                 Example         Compar. Ex.                                          evaluation items                                                                         8         9      10     5    6                                     ______________________________________                                        blocking resistance                                                                      ◯                                                                           ◯                                                                        ◯                                                                        X    ◯                           Flowability 6.0 5.0 6.0 5.0 3.0                                               gloss % 99 98 99 90 92                                                        adhesive strength 100 100 100 85 82                                           Erichsen value ◯ ◯ ◯ X ◯      impact resistance ◯ ◯ ◯ X .largecirc                                            le.                                   ______________________________________                                    

EXAMPLE 11

423.1 parts of epoxy resin [B-2] obtained by Example 6,31.2 parts ofbisphenol A, 50.5 parts of methylisobutyl-ketone and 0.5 part oftriethylamine are added to a 1 liter size glass separable flask equiptwith a stirrer, a thermometer, a nitrogen gas introducing pipe and acondenser. With constant stirring under nitrogen gas flow, thetemperature of contents in flask is raised to 160° C., and furtherreacted for 2 hours at 150˜160° C. After the reaction, the temperatureis raised to 200° C. for 2 hours and xylene is vaporized off from thesystem. When the temperature reached to 200° C., contents are removed,thus the solid epoxy resin [C-1] whose epoxy equivalent is 2140 g/eq(value of solid portion), non volatile portion is 99.8% and solutionviscosity (diluted to 40 wt % resin concentration by n-butylcarbitol andmeasured at 25° C. by Gardner Holdt viscometer is Z2˜Z3 is obtained. InExamples hereafter the solution viscosity is measured in the same way

EXAMPLE 12

The same experiment to Example 11 is made except using 423.1 parts ofepoxy resin [B-2] obtained in Example 6, 36.1 parts of bisphenol A, 51.1parts methylisobutylketone and 0.5 parts of triethylamine, and the solidepoxy resin [C-2] whose epoxy equivalent is 2680 g/eq (value of solidportion), non volatile portion is 99.5% and solution viscosity is Z4˜Z5is obtained.

EXAMPLE 13

The same experiment to Example 11 is made except using 423.1 parts ofepoxy resin [B-2] obtained in Example 6, 38.2 parts of bisphenol A, 51.3parts of methylisobutylketone and 0.5 parts of triethylamine, and thesolid epoxy resin [C-3] whose epoxy equivalent is 3180 g/eq (value ofsolid portion), non volatile portion is 99.4% and solution viscosity isZ6 is obtained.

GPC chart of this solid epoxy resin is shown in FIG. 7, and Infra redspectrum chart is shown in FIG. 9.

EXAMPLE 14

142.0 parts of the phenolic hydroxide group containing modified resin[A-1] obtained in Example 11, 423.1 parts of the epoxy resin [B-2]obtained in Example 6 are added together with 62.8 parts ofmethylisobutylketone into a 1 liter size glass separable flask whichequipts with a stirrer, a thermometer, a nitrogen gas introducing pipeand a condenser. The temperature is raised to 120° C., and resin iscompletely dissolved in MIBK. Then, 0.5 parts of trimethyl amine isadded and reacted likely to Example 11. The solid epoxy resin [C-4]whose epoxy equivalent is 1960 g/eq (value of solid portion), nonvolatile portion is 99.6% and solution viscosity is Z3 is obtained.

EXAMPLE 15

The same experiment to Example 11 is made except using 171.3 parts ofmodified phenolic hydroxide group containing resin [A-1] obtained inExample 1, 423.1 parts of epoxy resin [B-2] obtained in Example 6, 66.0parts of methylisobutylketone and 0.5 parts of triethylamine, and thesolid epoxy resin [C-5] whose epoxy equivalent is 2,440 g/eq (value ofsolid portion), non volatile portion is 99.5% and solution viscosity isZ5˜Z6 is obtained.

EXAMPLE 16

The same experiment to Example 11 is made except using 184.8 parts ofphenolic hydroxide group containing modified resin [A-1] obtained inExample 1, 423.1 parts of epoxy resin [B-2] obtained in Example 6, 67.5parts of methylisobutylketone and 0.5 parts of triethylamine, and thesolid epoxy resin [C-6] whose epoxy equivalent is 2,750 g/eq (value ofsolid portion), non volatile portion is 99.4% and solution viscosity isZ6 is obtained.

EXAMPLE 17

The same experiment to Example 11 is made except using 400 parts ofepoxy resin [B-2] obtained in Example 6, 49.3 parts of bisphenol A, 49.9parts of xylene and 0.5 parts of n-butyltriphenylphosphoniumbromide, andthe solid epoxy resin [C-7] whose epoxy equivalent is 2,720 g/eq (valueof solid portion), non-volatile portion is 98.0% and solution viscosityis Z5˜Z6 is obtained.

EXAMPLE 18

The same experiment to Example 1 is made except using 142.1 parts ofphenolic hydroxide group containing modified resin [A-1] obtained inExample 1, 300 parts of epoxy resin [B-I] obtained in Example 6, 49.1parts of xylene and 0.5 parts of triethylamine, and the solid epoxyresin [C-8] whose epoxy equivalent is 2,650 g/eq (value of solidportion), non-volatile portion is 98.5% and solution viscosity is Z5˜Z6is obtained.

COMPARABLE EXAMPLE 7

As a solid type epoxy resin of Comparative Example [C' 1], EPOTHOTOYD-909 (product of TOHTO KASEI, BPA type epoxy resin; Epoxy equivalentis 2,200 g/eq, number average molecular weight is 6,100) is selected.FIG. 8 is the GPC chart of this solid epoxy resin.

COMPARABLE EXAMPLE 8

1,720 parts of YD-8125 (product of TOHTO KASEI, molecular distillationBPA type liquid epoxy resin; Epoxy equivalent is 172 g/eq, content ofα-diol is 0.8 meq/100 g, hydrolyzable chlorine contents is 0.01 wt %),992 parts of BPA, 300 parts of xylene and 0.4 parts of triethylamine areadded to the same reaction apparatus of Example 11. With constantstirring under nitrogen gas flow, the temperature of contents in flaskis raised to 160° C., and further reacted for 2 hours at 160˜170° C.After the reaction, the temperature is raised to 200° C., for 2 hoursand xylene is vaporized off from the system. When the temperaturereached to 200° C., contents are removed, thus the solid type epoxyresin [C' 2] whose epoxy equivalent is 2,450 g/eq (value of solidportion), non-volatile portion is 96%, solution viscosity is Z3˜Z4 andnumber average molecular weight is 7,100 is obtained.

COMPARATIVE EXAMPLE 9

450 parts of YD-019 (product of TOHTO KASEI BPA type epoxy resin; epoxyequivalent is 2,800 g/eq, number average molecular weight is 4,000) and150 parts of xylene are added to a 2 liter size glass separable flaskwhich has same function to that of Example 11, and the temperature ofcontents in flask is raised to 120° C. The resin is dissolved in 90minutes.

After cooled down below 100° C., 600 parts of ethanol is added andstirred for 30 minutes, contents is transferred to 2 liter sizeseparating funnel and settled down until the content completely separateto two layers. Then, xylene solution layer which locates lower is putback to the separable flask, and rinsed by methanol for 5 times. Xyleneis removed using rotary evaporator, and the solid epoxy resin [C' 3] isobtained, whose epoxy equivalent is 3,500 g/eq (value of solid portion),non volatile component is 99%,and softening point is 140° C. and anumber average molecular weight is 5,700.

EXAMPLE 19˜26

The solid epoxy resins [C-1]˜[C-8] which obtained in Examples 11˜18 areused. 401 parts of each resins are dissolved in 599 parts of xylene and600 parts of cyclohexanone and solutions of 25 wt % resin concentrationare obtained. To each solution, 100 parts of HITANOL 4010 (resol typephenol resin; product of HITACHI CHEMICAL) and 2 parts of 85% phospholicacid are added and stirred, and uniform coatings are obtained. Theobtained coatings are coated over the surface of aluminum plates of 0.3mm thickness by bar coater, baked at 200° C. for 10 minutes. Thus thetest pieces of 10 μm thickness coated film of Example 19˜26 areobtained.

COMPARATIVE EXAMPLE 10˜12

The solid epoxy resins [C' 1]˜[C' 3] which were obtained in ComparativeExamples 7˜9 are used. 417 parts of each resins are dissolved in 583parts of xylene and 600 parts of cyclohexanone and solutions of 25 wt %resin concentration are obtained. To each solution, 100 parts of HITANOL4010 and 2 parts of 85% phosphoric acid are added and stirred, anduniform coatings are obtained. The obtained coatings are coated over thesurface of aluminum plates of 0.3 mm thickness, baked at 200° C. for 10minutes. Thus the test pieces of 10 μm thickness coated film ofComparative Examples 10-12 are obtained.

The physical properties of bisphenol type epoxy resin obtained inExamples 11˜18 and Comparative Examples 7-9 are shown.

Further, the physical properties of bisphenol type epoxy resin obtainedin Example 19˜26 and Comparative Examples 10˜12 are shown in Table 5.

The analytical method of epoxy resin and evaluation method of coatedfilm are illustrated as follows.

1) Epoxy equivalent; Measured by JIS K 7236

2) Number-average molecular weight; GPC method

Apparatus: HPLC-8020 (product of TOHSO Co., Ltd.)

Column: 2 pieces of GMHXL+1 piece of G2000XL (product of TOHSO Co.,Ltd.)

Temperature: 35° C. Flow rate: 1 ml/min

Detector: R1 Calibration curve: polystyrene

3) Solution viscosity;

Measured by Gardner Holdt viscosimeter at 25° C.

4) Potassium permanganate consumption;

Specimen is dissolved in cyclohexanone and a varnish of 25 wt % solidconcentration is prepared. This varnish is coated over the surface of0.3 mm thickness aluminum plate using a bar coater so that the thicknessof dry coated film is 10 μm, dried up in 200° C. oven for 10 minutes,and thus prepared a test piece is prepared. The test piece is put into apressure bottle and city water which is treated by activated carbon ispoured so that the contact ratio of test piece to water is 1 ml/5 cm².The pressure bottle is sealed and placed into a retort sterilizingvessel and sterilized at 125° C. for 1 hour. After cooled down,potassium permanganate consumption of this water is measured by themethod disclosed in food and health law of Japan.

5) Adhesive strength;

100 squares checker mark of 1 mm×1 mm square are cut on the coatedsurface by a knife and a cellophane tape is stuck, then the stuck tapeis removed rapidly. Number of squares are measured by naked eyes.

6) Bending processing;

The coated plate is bent as the coated side to be the surface side andpressed by 20 kg/cm² pressure at 20° C. Then electric current is chargedto the bent portion using an enamel meter (electric tester) and ampereis measured. Degree of damage of the coated surface is ranked to 3levels based on the measured value of ampere.

◯: value of ampere is smaller than 1 mA

Δ: value of ampere is from 1 to 5 mA

X: value of ampere is bigger than 5 mA

7) Retort resistance;

The coated plate is treated by retort at 125° C. for 30 minutes and thewhitening of coated film is inspected by naked eyes and ranked tofollowing 3 levels.

◯: not whitened

Δ: partially whitened

X: whole surface is whitened

8) Maintenance of flavour;

The test piece whose both surface is coated are prepared. The test pieceis put into a pressure bottle and city water which is treated byactivated carbon is poured so that contact ratio of test piece to wateris 1 ml/5 cm². The pressure bottle is sealed and placed into a retortsterilizing vessel and sterilized at 125° C. for 1 hour. After cooleddown, the treated water is evaluated sensually in comparison with thewater by blank test.

◯: no change

Δ: slightly changed

X: remarkably changed

The properties solid epoxy resins [C-1]˜[C-8] obtained in Examples 11˜18and solid epoxy resins [C' 1]˜[C' 3] obtained in Comparative Examplesare shown in Table 4. Table 4

                  TABLE 4                                                         ______________________________________                                                   epoxy    Solution  Molecular                                                                            KMnO.sub.4                                 epoxy equivalent viscosity Weight Consumption                                 resin eq. g/eq G-H/25° C. Mn mg O/L                                  ______________________________________                                        Example                                                                         11 C-1 2,140 Z2˜Z3 6,000 1.6                                            12 C-2 2,680 Z4˜Z5 7,600 0.9                                            13 C-3 3,180 Z6 8,600 0.9                                                     14 C-4 1,960 Z3 5,700 2.6                                                     15 C-5 2,440 Z4˜Z5 7,100 1.9                                            16 C-6 2,750 Z6 7,900 1.7                                                     17 C-7 2,720 Z5˜Z6 7,500 2.1                                            18 C-8 2,650 Z5˜Z6 7,400 2.6                                            Copar. Ex.                                                                     7 C ' 1 2,200 Z4 5,700 21.0                                                   8 C ' 2 2,450 Z4 6,400 14.1                                                   9 C ' 3 3,500 Z4˜Z5 8,200 7.0                                        ______________________________________                                    

The physical properties of coated film of Example 19˜26 and ComparativeExamples 10˜12 are shown in Table 5.

                  TABLE 5                                                         ______________________________________                                        epoxy       adhesive bending  retort maintenance                                resin strength resistance resistance of flavor                              ______________________________________                                        Example                                                                         19 C-1 100 ◯  ◯ ◯                         20 C-2 100 ◯ ◯ ◯                          21 C-3 100 ◯ ◯ ◯                          22 C-4 100 Δ Δ ◯                                      23 C-5 100 ◯ ◯ ◯                          24 C-6 100 ◯ ◯ ◯                          25 C-7 100 ◯ ◯ ◯                          26 C-8 100 ◯ ◯ ◯                          Compar. Ex.                                                                   10 C ' 1 100 Δ Δ X                                                11 C ' 2 100 ◯ ◯ Δ                              12 C ' 3 100 ◯ ◯ Δ                            ______________________________________                                    

Possibility for Practical Industrial Use

As clearly understood from the Examples, the modified phenolic hydroxylgroup containing resin [A] contains less volatile composition comparedwith the conventional well known modified resin, and the excellentcoated film which is superior at impact resistance and corrosionresistance can be prepared from the curable composition thereof [a]. Andthe solid epoxy resin [B] prepared by the epoxidation of said modifiedresin by epihalohydrin has more sharp distribution of molecular weightand higher glass transition temperature compared with the conventionalwell known modified resin, and has an excellent blocking resistance.Further, a coated film which has excellent adhesive strength, bendingability and impact resistance can be fabricated from the curable resincomposition thereof [b]. Furthermore, the solid epoxy resin [C] obtainedby addition polymerization reaction between said solid epoxy resin anddifunctional phenols can reduce the potassium permanganate consumptionby retort extraction remarkably in comparison with the conventional wellknown solid epoxy resins. Still further, from the curable compositionthereof [c] a coated film which is superior at maintenance of flavourcan be fabricated without spoiling adhesive strength, bending processingand retort resistance, and can provide a coating composition which isespecially useful as the inner surface coating of a can for beverage.

We claim:
 1. An epoxy resin which is solid at room temperature and whichcomprises the product of epoxidizing a modified phenolichydroxyl-containing resin having a low free difunctional phenol contentcomprising a resin of formula (1) ##STR3## wherein X represents aresidue of difunctional phenol and n is 0 or a positive integer; andwherein the X's at different positions may be the same or different;saidresin having a phenolic hydroxyl group equivalent of from 300 to 1200q/eg; and, wherein residues of unreacted difunctional phenol is lessthan 5% by weight of the resin, with an epihalohydrin,said epoxy resinhaving an epoxy equivalent in the range of 450 to 2500 g/eq.
 2. Theepoxy resin which is solid at room temperature according to claim 1further reacted with difunctional phenol to provide an epoxy equivalentof from 1,500 to 60,000 g/eq and a number average molecular weight offrom 3,000 to 15,000.
 3. The room temperature solid epoxy resin of claim2, characterized by a potassium permanganate consumption value smallerthan 5 mg O/L, wherein said value is measured on extracted water whichis prepared by adding, by a ratio of 1 ml water to 5 cm² area of uncureddry film having a thickness of about 10 μm and heat treated at 125° C.at high pressure for 1 hour in a sealed bottle.